Pin-type synchronizers of the general type disclosed herein are well known in the prior art as may be seen by reference to U.S. Pat. Nos. 2,667,955; 3,910,390; 4,018,319; 4,478,321 and 4,989,706, the disclosures of these patents are incorporated herein by reference.
Pin-type synchronizers generally include an axially slidable clutch collar that is mounted on a splined portion of a shaft on which a pair of axially spaced gears are rotatably mounted. The clutch collar is provided with jaw clutch teeth which are adapted to engage complimentary jaw clutch teeth formed on the rotatable gears to positive clutch a selected one of the gears to the shaft. The clutch collar is formed with a radially extending flange having two sets of circumferentially spaced openings extending axially therethrough and parallel to the rotational axis of the shaft. Disposed through one set of the openings are pins which are rigidly fixed at their ends to friction rings that are adapted to cooperate with friction surfaces affixed to the aforementioned gears. The pins, usually called blocker pins, have reduced central portions that define radially outwardly extending shoulders adapted to cooperate with peripheral edges of the openings for blocking axial movement of the flange relative to the friction rings during nonsynchronous rotation of the shaft and a selected one of the gears. Disposed through the other set of openings, which are alternately spaced between the blocker pin openings, are longitudinally split pin assemblies which are freely received at their ends in oblong recesses formed in mutually facing surfaces of the friction rings. Each split pin assembly includes a pair of members forming a centrally located annular groove which is biased into engagement with the peripheries of the associated split pin opening by springs sandwiched between the members. As is well known, the split pin assemblies cause one of the friction rings to engage a friction surface of a selected one of the gears in response to initial axial movement of the flange, thereby effecting limited relative rotation of the flange and friction rings during the aforementioned nonsynchronous condition for assuring blocking engagement by the blocker pins.
While the above mentioned synchronizer assemblies have been widely used for many years, problems have been associated with the springs sandwiched between the members of the split pin assemblies. One configuration of the springs have been prone, during certain operating conditions, to partially escape from between the split pin members and thereby cause the synchronizer assembly to jam.